These "incentivized" reviews skewed product ratings, and were ultimately disappointing and in some regard misleading customers. Data shows that an incentivized review averaged a 4.74 out of 5 rating, while a non-incentivized rating received just a 4.36 average review.

Amazon wants an online shopping experience that's quick, easy, price competitive and perhaps most importantly, honest and trustworthy. If users log in to purchase a new product and see that its rated a 4.74 out of 5, many will assume that it's of high quality and worthy of a purchase.

But if a majority of those reviews came from a customer who received that product for free, it's likely that they have a more positive bias. Given that Amazon has boomed into a colossal player in the retail sector, its customers' trust is ever so important.

Losing that could lead to lost sales. And in a world where seemingly every retailer is trying to combat Amazon, that's not something the company wants to see happen.

Shares of Amazon closed at $780.12 Wednesday, down 0.7%.

Fresh off its capital raise in September, Airbnb is looking to put some of that money to work in China. It raised $555 million at a valuation of $30 billion -- making many wonder when an IPO will be on the way.